Analyte concentration determination in physiological samples is of ever increasing importance to today's society. Such assays find use in a variety of application settings, including clinical laboratory testing, home testing, etc., where the results of such testing play a prominent role in the diagnosis and management of a variety of disease conditions. Analytes of interest include glucose for diabetes management, cholesterol for monitoring cardiovascular conditions, drugs for monitoring levels of therapeutic agents, identifying illegal levels of drugs, and the like. In response to this growing importance of analyte concentration determination, a variety of analyte concentration determination protocols and devices for both clinical and home testing have been developed.
In determining the concentration of an analyte in a physiological sample, a physiological sample must first be obtained for testing. However, obtaining and testing the sample often involves cumbersome and complicated procedures. Unfortunately, successful manipulation and handling of multiple test elements, such as an analyte tester, e.g., a test strip, lancing members, meters and the like is to a great extent dependent on the visual acuity and manual dexterity of the user, which, in the case of people with diabetes for example, is subject to deterioration over the course of the disease state. In extreme cases, for people who have significant loss of sight, hand-eye coordination and fingertip sensation, testing procedures can become significantly difficult and require additional assistance from ancillary devices or personnel.
A typical procedure for making an analyte concentration measurement with the use of an analyte tester such as a tester configured as a test strip or the like involves the following actions or steps (but not necessarily in the order given): (1) removing testing supplies from a carrying case, (2) grasping the lancing device and removing a lancing device loading cap or door, (3) removing and disposing of a used lancet from the lancing device, (4) inserting a new lancet in the lancing device, (5) twisting off a protective cap from the lancet, (6) replacing the lancing device cap, (7) cocking the lancing device, (8) opening a tester vial/container, (9) removing a tester from the container and inserting or interfacing it with a meter, (10) holding the lancing device to the skin, (11) firing the lancing device, (12) removing the lancing device from the skin, (13) extracting a sample from the incised area of skin, (14) applying sample to the tester and obtaining results of the measurement; (15) disposing of the tester, (16) cleaning the test site, and (17) returning supplies to the carrying case. Of course, certain analyte measurement systems and protocols may involve fewer or more steps.
One manner of reducing the number of actions is by the use of integrated devices which combine multiple functions in order to minimize the handling of testers and/or lancing components which may lead to contamination of the components and/or injury to the user, especially in those instances where the user has diminished fingertip sensation and visual acuity. In this regard, certain tester dispensers are configured to both store and advance successive testers upon actuation. Examples of such devices for dispensing test strips are presented in U.S. Pat. Nos. 5,510,266; 5,660,791; 5,575,403; 5,736,103; 5,757,666; 5,797,693; 5,856,195 and PCT Publication WO 99/44508. Some of these test strip dispenser devices also include meter functionality for testing physiological fluid.
Another class of devices designed to decrease the number of steps required in analyte concentration determination assays includes automatic or semi-automatic lancing devices. U.S. Pat. No. 6,228,100 discloses a structure configured for sequential firing of a number of lancets, one at a time, in order to eliminate the requirement that a user remove and replace each lancet individually before and after use. However, this device does not include any tester components or functions.
Attempts have been made to combine a lancing-type device with various other components involved in the analyte concentration determination procedure in order to simplify the analyte concentration determination assay process. For example, U.S. Pat. No. 6,099,484 discloses a sampling device which includes a single needle associated with a spring mechanism, a capillary tube associated with a pusher, and a test strip. An analyzer may also be mounted in the device for analyzing the sample. Accordingly, the single needle is displaced toward the skin surface by un-cocking a spring and then retracting it by another spring. A pusher is then displaced to push the capillary tube in communication with a sample and the pusher is then released and the fluid is transferred to a test strip through the capillary tube.
U.S. Pat. No. 5,820,570 discloses an apparatus which includes a base having a hollow needle and a cover having a membrane, whereby the base and cover are connected together at a hinge point. When in a closed position, the needle is in communication with the membrane and fluid can be drawn up through the needle and placed on the membrane of the cover.
There are certain drawbacks associated with each of the above devices and techniques. For example, the devices disclosed in the aforementioned patents are configured to test the sample at a site distant from the lanced site, thereby requiring the sample to be moved from the lanced site to another area for testing. Accordingly, in the case of the '484 patent, sample is moved through a capillary tube to a test strip and in the case of the '570 patent sample is moved through the needle to a membrane. While effective at moving the sample to the site of testing, a significant amount of sample may be lost during the transport process using such methods and devices, e.g., sample may adhere to the sides of the capillary tube, needle or the like. To compensate for such sample loss, such devices require a greater amount of sample from the incision area in order to perform an accurate test at the testing area, such that oftentimes the user needs to “milk” the initial lanced site to extract the required amount of sample therefrom or may need to lance yet another site. Both options are difficult for a user suffering from diabetes and have significant pain associated with them as well.
However, in many instances, the user is not aware that an insufficient amount of sample has been contacted with the tester or additional sample can not be provided in a timely manner. In such cases, a tester is wasted as the tester having insufficient amount of sample must be discarded and another test must be performed with a new tester, thereby increasing the cost of analyte concentration determination.
As such, there is continued interest in the development of new devices and methods for use in the determination of analyte concentrations in a physiological sample. Of particular interest would be the development of integrated devices, and methods of use thereof, that are efficient, simple to use, able to determine whether a sufficient amount of sample is present before contacting the sample with a tester and which require minimal sample amounts in order to perform an accurate analyte concentration determination.